Naegleria Fowleri

Written by: Jonah ‘23
Edited by: Jordan Feldman ‘24 and Chris Shin ‘24

Adapted from https://www.cdc.gov/parasites/naegleria

A young boy and his friends spent a mild summer afternoon playing and swimming in a small lake. A few days later he developed a high fever, headache, and began vomiting. His parents brought him to a doctor who diagnosed him with a bacterial infection and sent him home with antibiotics. Shortly afterward, he suffered a seizure, and his concerned parents brought him to the hospital where doctors feared he may have meningitis. Worried that his condition may deteriorate rapidly as is seen in many meningitis patients, they began administering high doses of antibiotics, took a sample of his CSF (cerebrospinal fluid), and a CT scan of his head to confirm their diagnosis. [4] The sample showed signs of inflammation, but the CT scan revealed nothing diagnostic. Despite aggressive treatment his condition continued to deteriorate, and he lapsed into a coma and died two days later. Puzzled by the sudden death and ineffective treatment, an autopsy was performed to understand the unusual circumstances of his death — a reexamination of his CSF now revealed the presence of an amoeba, Naegleria Fowleri. This is the typical progression of a patient infected by this disease. [1], [9]

N. Fowleri is an amoeba commonly found in bodies of warm freshwater across the United States. [2] When water containing the amoeba enters the nose it can cause a life-threatening condition known as Primary Amebic Meningoencephalitis (PAM) [1]. Once these amoebae enters the nose they follow the olfactory nerve through the cribriform plate into the brain where they begin feeding on brain cells [7] with a specialized appendage called an amoebostome. [3] Unsurprising, this process causes rapid and severe brain damage, that manifests as a multitude of physical and neurological symptoms including splitting headaches, high fevers, nausea, vomiting, confusion, and irritability. The condition is nearly always fatal with patients lapsing into a coma before succumbing to the infection a few days after symptoms present. [9]

To make matters worse, diagnosis of this condition is exceedingly challenging. Symptoms are easily mistaken for various forms of meningitis. Unfortunately, the antibiotics used to treat meningitis have virtually no effect on N. Fowleri. [5] To confirm a diagnosis of PAM, a sample of CSF must be extracted and examined. However, the amoeba may be destroyed by the process of preparing the sample. [1] Further complicating matters, any drug that could treat the disease must cross the blood brain barrier, a challenge which poses virtually no difficulty for N. Fowleri. [8] Several drugs have shown promise in vitro, but the blood-brain barrier likely hinders their ability to treat human patients. Indeed, the patient outcomes for infection are miserable. Only 4 people in the US have survived the infection in the last half a century [6].

Public health efforts surrounding N. Fowleri also pose an uphill battle. The disease is obscure and poorly understood. When it does reach public attention it is sensationalized by the media as “the brain-eating amoeba.” [2] Currently, there is no test that can readily determine the presence of N. Fowleri in a body of water [6]. Even if such a test was developed, the correlation between N. Fowleri’s presence of the amoeba in a body of water and infection is not understood. However, as terrifying as PAM may seem, there are significant hindrances to the disease’s ability to pose a significant threat. First, given the extreme rarity of PAM, it is likely the vast majority of people who are exposed never fall ill. Second, infection can only occur through the unusual nasal route; drinking water contaminated by N. Fowleri is safe according to the CDC. [6] 
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However there are two reasons that PAM should be taken seriously. For one, those who are infected are most often healthy children and young adults who are the most likely to spend the time in water sources containing N. Fowleri. The other is climate change. While chances of infection still remain exceedingly slim, a likely reason for the growing prevalence of PAM is that it is warming temperatures. A recent study from the CDC found that while the number of yearly cases in the US has not dramatically increased, the disease’s range is slowly creeping northwards at a rate of about 8 miles per year. [2] Another study suggested that shorter winters and polluted waters gives the amoeba a longer time and more favorable setting in which to procreate. [9] While N. Fowleri is certainly not a cause for alarm, this insidious disease’s spread is quite possibly yet another creeping symptom of our environmental indifference.

​Works Cited:

[1]Barnett N, Kaplan A, Hopkin R, Saubolle M, Rudinsky M. Primary amoebic meningoencephalitis with Naegleria fowleri: Clinical review. Pediatric Neurology [Online]. 1996; 15(3): 230-234. https://doi.org/10.1016/S0887-8994(96)00173-7.
[2] Gharpure R, Gleason M, Salah Z, Blackstock AJ, Hess-Homeier D, Yoder JS. Geographic Range of Recreational Water–Associated Primary Amebic Meningoencephalitis, United States, 1978–2018. Emerg Infect Dis. [Online]. 2021; 27(1): 271-274. https://dx.doi.org/10.3201/eid2701.202119
[3] Marciano-Cabral F, John DT. Cytopathogenicity of Naegleria fowleri for rat neuroblastoma cell cultures: scanning electron microscopy study. Infect Immun. 1983; 40(3): 1214-1217. doi:10.1128/IAI.40.3.1214-1217.1983
[4] Mayo Clinic. Meningitis. [Internet] [February 28, 2021]. Available from: https://www.mayoclinic.org/diseases-conditions/meningitis/diagnosis-treatment/drc-20350514
[5] Weiss H. The Brain-Eating Amoeba Is a Nearly Perfect Killer [Internet] [February 28, 2021]. Available from: https://www.theatlantic.com/science/archive/2019/07/how-brain-eating-amoeba-kills/594964/.
[6] CDC. General Information [Internet] [February 28, 2021]. Available from: https://www.cdc.gov/parasites/naegleria/general.html.
[7] Cervantes-Sandoval I, Serrano-Luna J, García-Latorre E, Tsutsumi V, Shibayama M. Characterization of brain inflammation during primary amoebic meningoencephalitis. Parasitology International [Online]. 2008; 57(3): 307-313. https://doi.org/10.1016/j.parint.2008.01.006.
[8] Gholipour B. Brain-Eating Amoeba: How One Girl Survived. [Internet] [February 28, 2021]. Available from: https://www.livescience.com/38897-how-to-survive-a-brain-eating-amoeba.html.
[9] Kemble S K, Lynfield T, DeVries A, Drehner D, Pomputius, III W, Beach M, Visvesvara G, Silva A, Hill V, Yoder J, Xiao L, Smith K, Danila R. Fatal Naegleria fowleri Infection Acquired in Minnesota: Possible Expanded Range of a Deadly Thermophilic Organism. Clinical Infectious Diseases [Online]. 2012; 54(6): 805–809. https://doi.org/10.1093/cid/cir961